dark fiber (non-lit/unused fiber) is all dependent on length, pair count, what it has to cross (railroads, water, etc.), arial or buried... Few companies offer it too - contact L3, or your telco, or similar bandwidcth provider. Oh and you'll need the equipment to "light" it.
Most cities demand that cable providers lay dark fiber to be used in the future if they wish to gain the rights of cable tv service in the area. Some cities do not do this though such as Daytona Beach - where they are basically a competitor to Time Warner (The city itself is a competitor when it comes to laying fiber)
If you are interested in obtaining this, I have a guy that we buy all our fiber though. He is a broker of sorts for several different companies to keep your prices low. PM me and I will get you the name/number.